Add `smartcn_word` & `smartcn_sentence` back for backwards compatibility

In f4d0d27 the deprecated `smartcn_sentence` tokenizer and deprecated
`smartcn_word` token filter were removed as the new all in one
`smartcn_tokenizer` should be used instead. However for those with pre-existing
indices with mappings that reference the deprecated tokenizer and token filter
this changes causes indexing and search errors.

This change preserves the `smartcn_sentence` tokenizer name and aliases it to
the new `smartcn_tokenizer`. The change set also reintroduces a `smartcn_word`
token filter that is a noop filter. The result of these changes should allow
elasticsearch instances with the existing deprecated mappings to upgrade and
take advantage of the new tokenizer in lucene.

(cherry picked from commit 25a0071)

Closes #29